Non-contact deviation measurement system

ABSTRACT

A non-contacting deviation measurement system projects a first line and a second line upon a surface of an object. The projections of the first line and second line are arranged to overlap at an intersection line oriented at a nominal location such that when the surface is oriented at the nominal location, the intersection line appears on the surface. As the location of the surface deviates from the nominal location, the first line and second line as projected upon the surface move away from one another. The distance between the lines may be used to calculate the deviation from the nominal location. The deviation calculated may be compared to a predetermined maximum allowable deviation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of and claims priority to U.S. patentapplication Ser. No. 13/185,395, filed Jul. 18, 2011, now U.S. Pat. No.9,134,164, which is a Continuation of and claims priority to U.S. patentapplication Ser. No. 12/131,613, filed Jun. 2, 2008, now U.S. Pat. No.7,983,873, which is a Continuation of and claims priority to U.S. patentapplication Ser. No. 11/329,215, filed Jan. 10, 2006, now U.S. Pat. No.7,383,152, the entire contents of which are hereby incorporated hereinby reference.

BACKGROUND OF THE INVENTION

This invention relates generally to a measuring system and morespecifically to a non-contacting deviation measurement system that maybe used, for example, to determine whether the level of propellant in aprojectile casing falls within predetermined acceptable ranges.

Projectiles such as bullets and other small caliber ammunition areavailable in a variety of standard sizes, and as such their structureand function are well known. Projectiles are often manufactured using anassembly line wherein a predetermined amount of propellant is dispensedinto a cartridge casing. Prior to insertion of the bullet, the level ofpropellant is measured to determine whether the actual amount ofpropellant falls within a predetermined range deemed acceptable for theparticular projectile being manufactured.

Existing mechanical propellant level measurement systems generally lowera probe into the casing until the probe contacts the upper surface ofthe propellant. The height of the probe is then analyzed to determinethe height of the propellant column in the casing. The mechanical natureof the contacting probe is subject to inherent variations or errors inthe measurements, for example due to slanted propellant in the casing orpropellant yielding to the weight of the probe.

With the development of efficient modern propellants, smaller volumes ofpropellant are required for a given projectile. Thus, the level ofprecision and accuracy desired in measuring propellant levels may exceedthe capabilities of mechanical probetype measurement systems.

There remains a need for a measuring system capable of repeatableaccurate measurements of high sensitivity. Preferably, the measuringsystem does not contact the object being measured.

All U.S. patents and applications and all other published documentsmentioned anywhere in this application are incorporated herein byreference in their entirety.

Without limiting the scope of the invention a brief summary of some ofthe claimed embodiments of the invention is set forth below. Additionaldetails of the summarized embodiments of the invention and/or additionalembodiments of the invention may be found in the Detailed Description ofthe Invention below.

A brief abstract of the technical disclosure in the specification isprovided as well only for the purposes of complying with 37 C.F.R. 1.72.The abstract is not intended to be used for interpreting the scope ofthe claims.

BRIEF SUMMARY OF THE INVENTION

In one embodiment, a deviation measuring system comprises a firstprojector projecting a first line and a second projector projecting asecond line. The projections are oriented such that the first lineoverlaps the second line at an intersection line. The intersection lineis oriented at a nominal location. An optical sensor is positioned tocapture an image of the projections of the first line and the secondline upon a surface of an object. Analysis software is used to analyzethe captured image and calculate the deviation between a location of thesurface and the nominal location.

In another embodiment, a method comprises providing a propellant columnto be measured and projecting a first line and a second line onto asurface of the propellant column. The projections are oriented such thatthe first line overlaps the second line at an intersection line, theintersection line oriented at a nominal height. The method furthercomprises measuring an average distance between the first line and thesecond line as projected onto the surface of the propellant column andcalculating a height deviation between the nominal height and thesurface of the propellant column. The calculation is performed using theaverage distance measured and an intersection angle between theprojection of the first line and the projection of the second line.

These and other embodiments which characterize the invention are pointedout with particularity in the claims annexed hereto and forming a parthereof. However, for a better understanding of the invention, itsadvantages and objectives obtained by its use, reference should be madeto the drawings which form a further part hereof and the accompanyingdescriptive matter, in which there are illustrated and described variousembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the invention is hereafter described withspecific reference being made to the drawings.

FIG. 1 shows an embodiment of a non-contacting measuring device.

FIG. 2 shows the projection of laser lines in an embodiment of theinvention.

FIG. 3 shows a cross section of the laser lines illustrated in FIG. 2.

FIG. 4 shows a side view of an embodiment of the invention and exampleupper surfaces of an object being measured.

FIGS. 5-7 show the projections of lines onto the examples of uppersurfaces shown in FIG. 4.

FIG. 8 shows a side view of an embodiment of the invention.

FIG. 9 shows a projection of lines onto an example upper surface of anobject being measured.

FIG. 10 shows another projection of lines onto an example upper surfaceof an object being measured.

FIG. 11 shows a side view of an embodiment of the invention and exampleupper surfaces of an object being measured. Each upper surface is cantedabout an axis that is parallel to the projected lines.

FIGS. 12-14 show the projections of lines onto the examples of uppersurfaces shown in FIG. 11.

FIG. 15 shows a side view of an embodiment of the invention and exampleupper surfaces of an object being measured. Each upper surface is cantedabout an axis that is perpendicular to the projected lines. The view ofFIG. 15 is taken from the same location as the view of FIG. 11.

FIGS. 16-18 show the projections of lines onto the examples of uppersurfaces shown in FIG. 15.

FIG. 19 shows another embodiment of the invention.

FIGS. 20-22 show the projections of lines onto the examples of uppersurfaces shown in FIG. 19.

FIG. 23 shows a flowchart for a procedure for measuring an object usingan embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

While this invention may be embodied in many different forms, there aredescribed in detail herein specific preferred embodiments of theinvention. This description is an exemplification of the principles ofthe invention and is not intended to limit the invention to theparticular embodiments illustrated.

For the purposes of this disclosure, like reference numerals in theFigures shall refer to like features unless otherwise indicated.

The relative orientations described herein (i.e. horizontal, vertical,etc.) assume a horizontal platform surface and a measuring system thatis oriented vertically above the platform surface. It should beunderstood that the invention is not limited to specific horizontal andvertical components, and that the use of such terms indicates theorientation of components relative to one another, and not necessarilyrelative to any particular fixed coordinate system.

In some embodiments, a measurement device 10 may be used to measure theheight of a column of propellant, for example within a projectilecasing. The measurement device 10 may compare the measured height to apredetermined nominal height, determine deviance from the predeterminednominal height, and evaluate whether the deviance is withinpredetermined acceptable ranges.

FIG. 1 shows an embodiment of the measurement device 10, which mayinclude a mount 16, a first light projector 30, a second light projector40, an optical sensor 60, a processor 12 and a tray 14. The tray 14 maycomprise a surface suitable for supporting an object that may bemeasured by the measurement device 10, such as a projectile casing 18that may be at least partially filled with propellant 20. In someembodiments, the tray 14 may comprise a conveyor or other moveabledevice that may also be used to transport one or more projectile casings18.

The first light projector 30 may comprise a light source and may projectlight, such as laser light, in a first line 32. The second lightprojector 40 may comprise a light source and may project light, such aslaser light, in a second line 42. In some embodiments, each lightprojector 30, 40 may comprise an independent light source generatinglight, such as laser light. In some embodiments, each light projector30, 40 may receive and direct light from a common light source. In someembodiments, each light projector 30, 40 may comprise a laser linegenerator such as a Micro-Focus Laser Diode Line Generator part#NT55-916 available from Edmund Optics.

The first line 32 and the second line 42 may be projected onto apropellant column 20. The optical sensor 60 may capture an image of theprojection of the lines 32, 42 as they appear on the propellant column20. The relative orientation of the lines 32, 42 may be used todetermine the height of the propellant column 20 relative to thepredetermined nominal height.

FIG. 2 shows a detail of an embodiment of the projections of the firstline 32 and the second line 42. The first line 32 and the second line 42are preferably parallel to one another and arranged to intersect at anintersection line 50. The intersection line 50 may be orientedhorizontally and may be located a predetermined nominal distance abovethe surface of the tray 14. The intersection line 50 represents thedesired nominal location of an upper surface of a propellant columncontaining a predetermined desired amount of propellant.

The first light projector 30 may be oriented on a first side 54 of theintersection line 50 and may project the first line 32 across theintersection line 50. Therefore, at locations above the intersectionline 50, the first line 32 may be to the first side 54 of theintersection line 50, and at locations below the intersection line 50,the first line may be to the second side 56 of the intersection line 50.The second light projector 40 may be oriented on the second side 56 ofthe intersection line 50 and may project the second line 42 across theintersection line 50. Therefore, at locations above the intersectionline 50, the second line 42 may be to the second side 56 of theintersection line 50, and at locations below the intersection line 50,the second line 42 may be to the first side 54 of the intersection line50.

The light projectors 30, 40 may be configured to have any suitable fanangle θ between the outmost rays 48 of the respective laser lines 32,42. Desirably, the fan angle θ of each light projector 30, 40 isselected to provide an intersection line 50 that has a length that isgreater than the diameter of the projectile casing 18 or propellantcolumn 20 (see FIG. 1) being measured. In some embodiments, the fanangle θ of each light projector 30, 40 may be 10 degrees.

The angle φ between the two beams projected by the respective lightprojectors 30, 40 may be any suitable angle that allows for measurementof the propellant column as herein described. The angle φ may generallyrange from slightly greater than 0 degrees to slightly less than 180degrees, and may be adjusted depending upon the height of the specificprojectile column 20 being measured and the distance between the lightprojectors 30, 40 and the tray 14. Applications particularly suitablefor the invention may range from 10 degrees for small diameter objectswhere the upper surface of the substrate being measured is relativelyfar below the top edge of the casing or vessel containing the substrate,to 170 degrees for objects where the substrate surface to be measured isnot obstructed by walls of the casing or vessel. Generally, as the angleφ between the two beams increases, the accuracy of the measurementsystem increases in resolution. In some embodiments, the angle φ betweenthe two beams may be 25 degrees.

Referring again to FIG. 1, the light projectors 30, 40 may be slidablyengaged with the mount 16. In some embodiments, the mount 16 maycomprise a curved track 17 for each light projector 30, 40. The track(s)17 may be oriented such that the angle φ between the two beams may beinfinitely adjusted while the intersection 50 of the lines 30, 40remains at the same location. Thus, the path of the track 17 may followa radius about the intersection line 50. In some embodiments, the lightprojectors 30, 40 may be connected by a mechanism that keeps the lightprojectors 30, 40 centered across the image sensor 60, or across avertical axis.

FIG. 3 shows a two-dimensional cross-section of the projections andexaggerated thicknesses of the first line 32 and second line 42 in anembodiment of the measurement device 10. The light projectors 30, 40 areeach focused to provide the thinnest possible line at the location ofthe intersection line 50.

The intersection line 50 is preferably oriented at a nominal heighth_(n) above the tray 14. The nominal height h_(n) may be adjusteddepending on the specific type of projectile casing 18 and propellant 20being used. The nominal height h_(n) represents the desired distancebetween a predetermined portion of a projectile casing 18 (see FIG. 1),such as the bottom of the projectile casing 18, and the desired nominalheight of the propellant column 20.

FIG. 4 shows a side view of an embodiment of the measurement device 10showing the projected paths of the first line 32 and the second line 42,and examples of a propellant column 20. A first example upper surface 22a of a propellant column 20 represents the level of propellant beinghigher than nominal. A second example upper surface 22 b of a propellantcolumn 20 represents the level of propellant being at the nominalheight. A third example upper surface 22 c of a propellant columnrepresents the level of propellant being lower than nominal.

FIGS. 5-7 show projections of the first line 32 and second line 42 onthe upper surface examples 22 a-22 c of the propellant column 20, forexample as would be seen by the optical sensor 60 of the measurementdevice 10. The propellant column 20 is preferably oriented such that acentral axis 21 of the propellant column 20 is centered between thelaser lines 32, 42 and positioned to intersect the intersection line 50.

FIG. 6 shows an example upper surface 22 b that is located at thenominal height h_(n), wherein the height of the propellant column 20 isat the desired nominal level. The first line 32 and the second line 42are projected onto the same location of the propellant column uppersurface 22 b and appear as a single line, i.e. the intersection line 50.

As the location of the upper surface 22 of the propellant column 20deviates from the nominal level, the width of the line formed by thefirst line 32 and the second line 42 begins to increase and willeventually transition into the two individual lines 32, 42. As thedeviation increases, the first line 32 and the second line 42 will moveaway from one another.

FIG. 5 shows an example upper surface 22 a that is located above thenominal height h_(n), wherein the height of the propellant column 20 isgreater than the desired nominal level. The first line 32 and the secondline 42 appear individually. The first line 32 is located to a firstside 54 of the axis 21 of the propellant column 20, and the second line42 is located to a second side 56 of the axis 21 of the propellantcolumn 20. As the location of the upper surface 22 a deviates a greaterdistance above the nominal height h_(n), the distance between the firstline 32 and the second line 42 increases.

FIG. 7 shows an example upper surface 22 b that is located below thenominal height h_(n), wherein the height of the propellant column 20 isless than the desired nominal level. The first line 32 and the secondline 42 appear individually, and the relative orientation of the twolines 32, 42 is reversed from that of FIG. 5. The first line 32 islocated to the second side 56 of the axis 21 of the propellant column20, and the second line 42 is located to the first side 54 of the axis21 of the propellant column 20. As the location of the upper surface 22b deviates a greater distance below the nominal height h_(n), thedistance between the first line 32 and the second line 42 increases.

The distance between the lines 32, 42 as projected on an upper surface22 of a propellant column 20 may be used to calculate the deviationbetween the desired nominal height h_(n) and the actual height of theupper surface 22.

FIG. 8 shows an example propellant column 20 having an upper surface 22that is lower than nominal. The deviation d from nominal represents thedistance between the intersection line 50 and the upper surface 22. Thedeviation d may be calculated using the angle φ between the two beamsand the distance a between the lines 32, 42 as projected onto the uppersurface according to the following function.

$d = \frac{a\;{\cot( \frac{\varphi}{2} )}}{2}$

In situations where the upper surface 22 is oriented above theintersection line 50, the same calculation may be used to determine thedeviation d. The relative location of each line 32, 42 may be used todetermine whether the upper surface 22 is above or below nominal, as theposition of the lines 32, 42 with respect to one another will reverseabove and below the intersection line 50. Therefore, in someembodiments, the first line 32 may be distinguishable from the secondline 42, for example by being projected in a different pattern (i.e. adashed line), a different color, etc.

The deviation d may be compared to a predetermined maximum acceptabledeviation allowed for the particular projectile or propellant column 20being measured. If the actual deviation d is less than the predeterminedmaximum acceptable deviation, the propellant 20 level is acceptable andthe particular item being measured may be allowed to continue down theassembly line. If the actual deviation d is greater than thepredetermined maximum acceptable deviation, the propellant 20 level isnot acceptable and the particular item being measured may be rerouted,discarded, etc.

FIG. 9 shows a top view of the propellant column 20 of FIG. 8, forexample as may be captured by the optical sensor 60. The two line 32, 42measuring device 10 is superior to a single line measuring systembecause the intersection line 50 provides a nominal reference thatremains centered in the field of vision of the optical sensor 60.

Further, the projection of the outer ends 34, 44 of each line 32, 42onto the tray 14 (outside of the propellant column 20) may be used toverify the nominal height h_(n) of the nominal line 50 above the tray14. Thus, the measuring device 10 may be self-calibrating by verifying anominal distance a_(n) between the ends 34, 44 of each line 32, 42 asprojected onto the tray 14. The nominal distance a_(n) may bepredetermined based upon the specific embodiment of the measuring device10 and the propellant column 20 being measured. The predeterminednominal distance a_(n) may be verified each time the measuring device 10measures a propellant column 20. In some embodiments, the lightprojectors 30, 40 may be mounted to a mounting device that can be movedin a vertical direction, and the system may be calibrated by setting thenominal distance a_(n) properly prior to each measurement.

In some embodiments, highlights of the lasers on the edge 19 of themouth of a casing 18 (see FIG. 1) may be used to determine the height ofthe mouth of the casing 18. This may be used for calibration,verification, etc.

In some embodiments, imaging software and a processor 12 (see FIG. 1)may be used to analyze an image of the lines 32, 42 and determine thedeviance d. The optical sensor 60 may capture an image of the lines 32,42 as they are projected upon the propellant column 20, for example asshown in FIG. 9. The optical sensor 60 may comprise any device suitablefor capturing an appropriate image. In some embodiments the opticalsensor 60 may be a DVT SmartImage Sensor available from CognexCorporation, such as the Legend 510 SmartImage Sensor.

The image may be analyzed using any software suitable for analyzing theimage and determining the distance a between the lines 32, 42. In someembodiments, the software may comprise DVT Intellect software availablefrom Cognex Corporation.

FIG. 10 shows an example of an image that may be captured by the opticalsensor 60 and analyzed to determine the distance a between the lines 32,42. As illustrated in FIG. 3, the lines 32, 42 are focused at theintersection line 50. Thus, as the height of the propellant column 20deviates from the nominal height, the projection of the lines 32, 42will increase in width and eventually transition into the two separatelines 32, 42. Therefore, in determining the distance a between the lines32, 42, the analysis software may actually determine the distancebetween opposed outer edges of the lines 32, 42.

The analysis software may determine the distance a by evaluatingportions of the lines 32, 42 that fall within an analysis area 62, whichmay have a length 63 and a width 64. The length 63 may be orientedperpendicular to the intersection line 50, may be of any suitabledimension and is preferably long enough to encompass the outer bounds ofthe possible locations of the lines 32, 42. Thus, the length 63 ispreferably equal to or greater than the diameter of the propellantcolumn 20. The analysis area 62 may have any suitable width 64. In someembodiments, the width 64 may be small in relation to the length 63. Insome embodiments, the width 64 may be approximately equal to four times(4×) the diameter of the grain size of the propellant 20 being measured,which eases measurement variation due to the granular structure of thesurface of the propellant column 20. Preferably, the analysis area 62 iscentered upon the propellant column 20.

In some embodiments, one or more calibration analysis areas 50 may bedefined, and may be used for calibration of the measurement device 10.

Preferably, the propellant columns 20 being measured will have an uppersurface 22 that is substantially flat and oriented substantiallyhorizontally. In some embodiments, a casing 18 may be tapped, vibratedor otherwise acted upon to encourage a flat and horizontally orientedupper surface 22 prior to being measured. In some embodiments, a pinwith a flat bottom may be lowered into the casing 18 to shape the uppersurface 22.

In some embodiments, a propellant column 20 being measured may have anupper surface 22 that is not horizontal. Various slopes and orientationsof an upper surface 22 may produce various orientations of line 32, 42projections.

FIG. 11 shows three examples of upper surfaces 22 d, 22 e, 22 f of apropellant column 20 that are not horizontal. Each upper surface 22 d,22 e, 22 f is canted about an axis that is parallel to the intersectionline 50. FIGS. 12-14 show examples of line 32, 42 projections onto theupper surfaces 22 d, 22 e, 22 f.

Although upper surface 22 e is not horizontal, the center of the uppersurface 22 e is oriented at the nominal height. Thus, the intersectionline 50 appears as a single line in FIG. 13.

FIGS. 12 and 14 show line projections upon canted upper surfaces 22 d,22 f oriented above and below nominal level, respectively. It can beseen that the lines 32, 42 are not centered across the central axis 21of the propellant column 20 (see FIGS. 5 and 7 for examples of when thelines 32, 42 are centered across the central axis 21 of the propellantcolumn 20). Thus, a midline 24 (see FIG. 14) drawn equidistant betweenthe lines 32, 42 does not pass through the axis 21. The offset 25indicates that the upper surface 22 d, 22 f is canted and the heightdeviates from the nominal height. The fact that the lines 32, 42 areparallel to one another indicates that the cant is across an axis thatis parallel to the intersection line 50.

FIG. 15 shows three examples of an upper surface 22 g, 22 h, 22 i of apropellant column 20 that is not horizontal. Note that the view of FIG.15 is taken from the same location as the view of FIG. 11. Each uppersurface 22 g, 22 h, 22 i is canted about an axis that is perpendicularto the intersection line 50. FIGS. 16-18 show examples of line 32, 42projections onto the upper surfaces 22 g, 22 h, 22 i.

Referring to FIG. 17, the lines 32, 42 are nonparallel to theintersection line 50, which indicates a cant about an axis that isperpendicular to the intersection line 50. The center 21 of the uppersurface 22 h is oriented at the nominal height, and thus the lines 32,42 intersect at the axis 21 of the propellant column 20.

FIGS. 16 and 18 show line projections upon canted upper surfaces 22 g,22 i oriented above and below nominal level, respectively. It can beseen that the intersection of the lines 32, 42 is offset from thecentral axis 21 of the propellant column 20. The offset 26 indicatesthat the upper surface 22 g, 22 i has deviated from nominal.

In operation, various orientations of actual upper surfaces 22 ofpropellant columns 20 may produce many variations in the appearance ofthe lines 32, 42 that differ from the examples illustrated herein. Theanalysis area 62 (see FIG. 10) is desirably shaped to minimize any errorimparted by orientation of the upper surface 22. Particularly, a smallwidth 64 dimension coupled with an analysis area 62 centered upon thepropellant column 20 leads to lines 32, 42 in the analysis area 62 thatare close together when the average upper surface 22 height is close tonominal, and lines 32, 42 that are farther apart as the average uppersurface 22 height deviates from nominal. This may be seen bysuperimposing an analysis area 62 onto FIGS. 5-7, 12-14 and 16-18.

When one or both of the lines 32, 42 are oriented at an angle to theintersection line 50, the distance a between the lines 32, 42 that iscalculated may comprise an average distance a between the lines 32, 42taken across the width 64 of the analysis area 62.

The inventive measurement device 10 has demonstrated the capacity ofmeasuring deviations within +/−0.005″. This figure is in contrast to theprior art mechanical probe-type measuring systems, wherein propellantsettling can cause variations of +/−0.05″ or more. The inventivemeasurement device 10 further has the capability of much higherresolutions depending on the angle φ (see FIG. 8) between the two laserprojections. A larger angle φ allows a higher sensitivity.

In some embodiments, the optical sensor 60 and analysis software may becapable of distinguishing the first line 32 from the second line 42, andthus, depending on the relative orientation of the lines 32, 42, may beable to indicate whether the deviation d is positive or negative (i.e.above or below nominal).

Referring to FIG. 1, in some embodiments, a third light projector 70 maybe used to project an additional line that may be used to determinewhether the deviation d is positive or negative. This may be useful insituations where the first line 32 is not distinguishable from thesecond line 42, for example when the light projected is identical, orwhen the optical sensor 60 or the analysis software is not capable ofdistinguishing the lines 32, 42 from one another.

FIG. 19 shows an embodiment of the measurement device 10 having a thirdlight projector 70, which may comprise a light source and may projectlight, such as laser light, in a third line 72. The third line 72 may beoriented perpendicular to the intersection line 50. The third line 72may be projected such that it will bisect the intersection line 50 atthe nominal height. Thus, the third line 72 will intersect the centralaxis 21 of the propellant column 20 when the upper surface 22 isoriented at the nominal height. The third line 72 may further beprojected at an angle to vertical such that when the upper surface 22 isabove nominal, the third line 72 will be offset from the axis 21 in onedirection, and when the upper surface 22 is below nominal, the thirdline will be offset from the axis 21 in an opposite direction.

FIGS. 20-22 show examples of line 32, 42, 72 projections onto theexample upper surfaces 22 j, 22 k, 221 shown in FIG. 19. FIG. 21 showsan upper surface 22 k oriented at the nominal level. The first line 32and the second line 42 overlap and form the intersection line 50. Thethird line 72 intersects the intersection line 50 at the central axis 21of the propellant column 20.

FIG. 20 shows an upper surface 22 j oriented above the nominal height.The first line 32 and the second line 42 appear separately, while thethird line 72 is offset from the axis 21 of the propellant column 20 ina first direction.

FIG. 22 shows an upper surface 221 oriented below the nominal height.The first line 32 and the second line 42 appear separately, while thethird line 72 is offset from the axis 21 of the propellant column 20 ina second direction. The second direction is opposite the first directionof FIG. 20. FIG. 22 also shows an analysis area 62 used to determinedeviation of the propellant column 20 from nominal, and a secondanalysis area 66 used to determine presence and location of the thirdline 72.

FIG. 23 shows a flowchart illustrating various steps that may beperformed in measuring the deviance d from nominal of the height of apropellant column 20. A casing 18 may be filled with propellant 20 andoriented within the field of view of the measuring device 10 upon thetray 14. In some embodiments, a casing 18 may be tapped to encourage ahorizontal upper surface 22 of the propellant column 20. The lines 32,42 may be projected upon the upper surface 22 of the propellant 20.

In some embodiments, an optional calibration step 80 may be performed. Acalibration 80 may be used to set the height of the projectors 30, 40 bychecking the distance a_(n) between the ends 34, 44 of the lines 32, 42as projected onto the tray 14 (see FIGS. 8 and 9). A calibration 80 mayalso verify the height of the mouth 19 of the casing 18 by verifying thepositions of highlights of the lines 32, 42 on the mouth 19 of thecasing 18. This step may also be used to verify the diameter of thecasing 18.

As shown in FIG. 1, the image sensor 60 may be fixedly attached to themount 16. Thus, the position of the image sensor 60 may be fixed inrelation to the intersection line 50. In a calibration procedure 80, themount 16, image sensor 60 and light projectors 30, 40 may be movedcollectively in relation to the tray 14, the propellant column 20 andthe casing 18 in order to set the nominal height h_(n).

Referring again to FIG. 23, an image of the lines 32, 42 as projectedonto the upper surface 22 may be captured 82 by the image sensor 60. Thecaptured image may be analyzed 84 by the analysis software. The distancea between the outer edges of the lines 32, 42 as they appear in theanalysis area 62 may be determined and used to calculate the deviationd. In some embodiments, a calibration 80 check may be performed at thistime. In some embodiment, the relative locations of the lines 32, 42 maybe used to determine the value (+/−) of the deviation d (above or belownominal) In some embodiments, the location of a third line 72 may beused to determine the value (+/−) of the deviation d.

The calculated deviation d may be compared 86 to a predetermined maximumallowable deviation. The amount of maximum allowable deviation may bedetermined according to the specific projectile being manufactured.

In situations where the actual deviation d is equal to or less than themaximum allowable deviation, the projectile is accepted 88 and allowedto continue down the assembly line.

In situations where the actual deviation d is greater than the maximumallowable deviation, the projectile is rejected 90 and does not continuedown the assembly line. The projectile may be discarded, or in someembodiments may be emptied and once again filled with propellant andanalyzed by the measuring device 10.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this field of art. All these alternatives andvariations are intended to be included within the scope of the claimswhere the term “comprising” means “including, but not limited to”. Thosefamiliar with the art may recognize other equivalents to the specificembodiments described herein which equivalents are also intended to beencompassed by the claims.

Further, the particular features presented in the dependent claims canbe combined with each other in other manners within the scope of theinvention such that the invention should be recognized as alsospecifically directed to other embodiments having any other possiblecombination of the features of the dependent claims. For instance, forpurposes of claim publication, any dependent claim which follows shouldbe taken as alternatively written in a multiple dependent form from allprior claims which possess all antecedents referenced in such dependentclaim if such multiple dependent format is an accepted format within thejurisdiction (e.g. each claim depending directly from claim 1 should bealternatively taken as depending from all previous claims). Injurisdictions where multiple dependent claim formats are restricted, thefollowing dependent claims should each be also taken as alternativelywritten in each singly dependent claim format which creates a dependencyfrom a prior antecedent-possessing claim other than the specific claimlisted in such dependent claim below.

This completes the description of the preferred and alternateembodiments of the invention. Those skilled in the art may recognizeother equivalents to the specific embodiment described herein whichequivalents are intended to be encompassed by the claims attachedhereto.

The invention claimed is:
 1. A deviation measuring system for apropellant column at least partially filling a projectile casing, thesystem comprising: a surface for placement of the projectile casing andthe propellant column; a first projector projecting a first line towardsthe propellant column and a second projector projecting a second linetowards the propellant column, the first line overlapping the secondline at an intersection line, the intersection line oriented at anominal height relative to the surface for placement of the projectilecasing and the propellant column; an optical sensor positioned tocapture an image of the projections of the first line and the secondline upon a surface of the propellant column; and a processor executingan analysis software to analyze the image and to calculate a deviationbetween a height of the surface of the propellant column and the nominalheight by using a distance a between the first line and the second lineas projected onto the surface of the propellant column wherein thedistance α is determined using the analysis of the image.
 2. Thedeviation measuring system of claim 1, wherein the first projector andthe second projector are focused at the intersection line.
 3. Thedeviation measuring system of claim 1, wherein the distance α comprisesan average distance between the first line and the second line in ananalysis area of the image.
 4. The deviation measuring system of claim3, wherein a dimension of the analysis area is equal to or greater thana diameter of the propellant column.
 5. The deviation measuring systemof claim 3, wherein a dimension of the analysis area is equal toapproximately 4 times a grain size of the propellant column.
 6. Thedeviation measuring system of claim 1, wherein the deviation iscalculated using an angle φ between the projections of the first lineand the second line according to the following formula:${deviation} = {\frac{a\;{\cot( \frac{\varphi}{2} )}}{2}.}$7. The deviation measuring system of claim 6, wherein the angle φbetween the projections of the first line and the second line fallswithin a range of 10 degrees to 170 degrees.
 8. The deviation measuringsystem of claim 1, wherein the surface for placement of the projectilecasing and the propellant column is a tray and the distance between thefirst line and the second line as projected upon the tray may be used toverify the nominal height of the intersection line.
 9. The deviationmeasuring system of claim 1, wherein the surface of the propellantcolumn is nonplanar.
 10. The deviation measuring system of claim 1,wherein the propellant column comprises a powder.
 11. The deviationmeasuring system of claim 1, wherein the intersection line ishorizontal.
 12. The deviation measuring system of claim 1, wherein avertical axis intersects the intersection line, and the projection ofthe first line is oriented at an angle to the vertical axis such thatthe first line is located to a first side of the vertical axis atlocations above the intersection line and located to a second side ofthe vertical axis at locations below the intersection line.
 13. Thedeviation measuring system of claim 12, wherein the projection of thesecond line is oriented at an angle to the vertical axis such that thesecond line is located to the second side of the vertical axis atlocations above the intersection line and located to the first side ofthe vertical axis at locations below the intersection line.
 14. Thedeviation measuring system of claim 1, further comprising a thirdprojector projecting a third line, the third line oriented perpendicularto the intersection line, the position of the third line as projected onthe surface of the propellant column and indicating whether an uppersurface is above or below the nominal height.
 15. A method for measuringdeviation of a propellant column at least partially filling a projectilecasing, the method comprising: providing, on a supporting surface, thepropellant column at least partially filling the projectile casing;providing a first projector for projecting a first line towards thepropellant column and a second projector for projecting a second linetowards the propellant column, the first projector and the secondprojector oriented such that the first line overlaps the second line atan intersection line, the intersection line oriented at a nominalheight, relative to the supporting surface; projecting the first lineand the second line onto a surface of the propellant column; measuringan average distance between the first line and the second line asprojected onto the surface of the propellant column; and calculating aheight deviation between the nominal height and a height of the surfaceof the propellant column using the average distance measured and anintersection angle between the projection of the first line and theprojection of the second line.
 16. The method of claim 15, wherein thestep of measuring the average distance between the first line and thesecond line as projected onto the surface of the propellant columnfurther comprises providing an optical sensor, capturing an image of theprojections of the first line and the second line upon the surface ofthe propellant column and analyzing the image to determine the averagedistance.
 17. The method of claim 15, wherein the step of calculating aheight deviation further comprises providing a processor and software toperform the calculation.
 18. The method of claim 15, further comprisingdetermining whether the calculated height deviation falls within apredetermined maximum acceptable height deviation.